1. Technical Field
The disclosure generally relates to charge circuits, and more particularly relates to a charging circuit using universal serial bus (USB) interface sleep technology.
2. Description of the Related Art
When the voltage of a battery of a portable electronic device, such as a mobile phone is insufficient, the battery can be charged via connecting the portable electronic device to a USB interface of a personal computer which implements USB interface sleep technology.
Referring to FIG. 3, a USB charging control system 1 used in a personal computer that implements the USB interface sleep technology often includes a charging control microchip 2, a USB transceiver 3, a southbridge microchip 4, and a USB connector 5. Control terminals S0 and S1 of the charging microchip 2 are operable to control data terminals D+ and D− of the charging control microchip 2. When the control terminals S0 and S1 are both set to logic 0, the USB charging control system 1 can be in a charging mode, and then the portable electronic device is electronically connected to the two data terminals D+ and D− via the USB connector 5, to obtain power from the charging control microchip 2. When the control terminals S0 and S1 are both set to logic 1, the data terminals D+ and D− are respectively connected to transmission terminals Y+ and Y− of the charging control microchip 2, then the USB charging control system 1 can be in a data transmission mode, and the portable electronic device can receive data from the personal computer via the USB connector 5, the USB transceiver 3, and the southbridge microchip 4.
However, it is a defect in the USB charging control system 1 that the portable electronic device can not obtain power from the personal computer before the operating system of the personal computer has been started. Furthermore, the charging mode and the data transmission mode are not interchangeable when the personal computer is in a sleep mode. Thus, inconvenience is caused.
Therefore, there is room for improvement within the art.